There are a couple of things people can do to make life a bit easier in the cold and in the dark. If there comes a time that your power suddenly goes down and you are left with no heat and/or no light, these suggestions may help you.
When it is very cold, and you do not own a space blanket or a sub-zero sleeping bag, you can use heavy-gauge aluminum foil, which you have sandwiched between two flannel or cotton sheets. You secure the foil in place with quick stitching and wrap it around yourself or the others in your family. You may want to make up a couple of these before the crisis hits. If not, they can be assembled in a few minutes on the spot. This wrap will reflect body heat back to the person and keep you quite warm in a cold situation. Another way to increase the efficiency of these blankets is to put a rubber sheet over the top when you lay down. This will amplify the amount of body heat that is retained and will also block the cold air and/or wind from penetrating through the home-made blanket, thus keeping you warmer still.
As for lighting, think reflection. If you only have one or two candles left and you want to produce as much light as you can, you can use aluminum foil, once again. Staple the aluminum foil to a wall behind the candle and to the wall opposite the candle. This will create a series of reflections, which will increase your lighting. Mirrors will work well for this, too, but I don't think most people have a lot of mirrors laying around. Using the aluminum foil will also help with your heat retention, so in this manner, it serves a double purpose.
Offered by Shekhina.
Space Blankets are one of the marvels of technology. Whenever we discuss any survival subject, certain assumptions are usually made about what you have available to you at the moment, and then apply what skill you have to using anything that is handy. So I'm making an assumption that if you happened to have a space blanket on you, most likely you would also have either some matches or a lighter of some type as well. The space blanket is plastic that has a layer of reflective foil coating, this coating reflects up to 80% of a persons body heat, so the obvious use is to simply wrap yourself up in it like a blanket. But the comment I wanted to make is that what we are trying to prevent is hypothermia, (a lowering of the bodys temperature). It doesn't have to be frigid conditions to die of hypothermia, of course the danger increases as the temps go down.
These space blankets make great shelter material as they are waterproof, you could make a decent tent out of one and combined with a fire placed properly, could provide more overall protection. I use them as fire reflectors. If you had a couple of them, one can be set up behind your fire and used to bounce the heat energy back towards the resting survivor in her shelter. Aluminum foil can also be used effectively for this same purpose by combining a natural feature of a rock or hillside and placing foil strategically close to the fire. Say you were at home with the power out? If you had a fireplace, a space blanket may be used in the same way, string it out between you and the heat source, reducing the amount of space to be heated and reusing the heat energy by reflecting it back to you. Caution, they are flammable, so be careful not to place them too close to your fire and lose the whole rig to a hot coal or spark. I love space blankets, I always keep them stashed away in my glovebox, airplane, boat, or what have you. They are cheap and small enough folded that there is no reason not to include them in your pack.
Offered by Matt.